Decoding Arrhythmias in Kids

Pediatric supraventricular tachycardia is the most common arrhythmia in children and often presents with a strikingly regular rate above 200/min in a child who looks better than expected. The key ED challenge is separating true SVT from sinus tachycardia, then escalating from vagal maneuvers to adenosine and synchronized cardioversion when needed.

Pediatric SVT Recognition and Treatment

• Regular fixed-rate tachycardia: Pediatric SVT usually shows a very regular rhythm with rates often above 200/min, sometimes over 220/min, and the child may appear surprisingly well despite the number.
• Sinus versus SVT clue: Rate variability is a useful bedside discriminator: sinus tachycardia speeds up and slows down with crying or distress, while SVT tends to stay locked at one rate.
• First-line vagal maneuvers: Vagal maneuvers are first-line therapy and work in about 50% of cases, with age-specific techniques ranging from ice to the face in infants to syringe Valsalva in older kids.
• Adenosine first drug: Adenosine is the usual first medication after failed vagal maneuvers, with beta-blockers, procainamide, and amiodarone as escalation options. We get into the practical sequencing in the episode.
• Verapamil and procainamide pearls: Verapamil should be avoided in children under 1 year, while procainamide is a useful option when WPW or antidromic AVRT is on the table and pediatric hypotension is less of a problem than in adults.
• Synchronized cardioversion threshold: Unstable patients or medication failures need synchronized cardioversion starting at 0.5 to 1 J/kg, with sedation choices that favor etomidate or midazolam and avoid ketamine-related tachycardia.